We have hybridized Drosophila melanogaster DNA sequences
to polytene chromosomes of D. silvestris. The results support Muller's hypothesis
that the chromosomal elements have been largely conserved in the evolution
of the genus Drosophila. As originally suggested by Carson, D. melanogaster
elements X, 2L, 2R, 3L, and 3R appear to correspond to chromosomes X, 3, 2,
5, and 4, respectively, in D. silvestris and the Hawaiian picture-winged species.